1. Field of the Invention
The invention relates to semiconductor technology and in particular to devices for low gate voltage and higher drain breakdown performance.
2. Description of the Related Art
In many applications it is desirable to have a variety of logic devices, memory devices and device capable of withstanding large transients (hereon referred to as power devices) all on a single substrate. One type of power device is a diffused metal-oxide-semiconductor transistor (DMOS).
Heretofore most lateral diffused metal oxide semiconductor, (LDMOS) structures built on a substrate with one or more other device structures have been formed by first forming a high voltage tank. The devices are isolated by field oxide (FOX) processes or shallow trench isolation (STI) regions. However, in a critical understanding, the inventors have found that the isolation (e.g., FOX) regions under the gate electrode have problems that lower the breakdown voltage.
A semiconductor device is disclosed to improve the breakdown voltages. The device comprises an additional dielectric block covering the FOX region thereof to improve the breakdown voltages. This structure effectively works but potentially increases the processing steps and cost thereof due to formation of the dielectric block. Thus, more cost-effective structures and processes are needed.